The 5U84 Primary Storage Shelf and the 5U84 Expansion Storage Shelf each use a 5U chassis. Each chassis contains two sliding drawers that are accessible from the front of the storage shelves. Each drawer can hold 42 Disk Drive In Carrier (DDIC) modules. The DDIC modules are installed in each of the drive drawer slots, which can hold a total of 84 disk drives. Each DDIC module holds one 3.5" SAS3, 7200 rpm hard disk drive, in 10-TB capacities. The disk drives and the DDIC modules are hot-swappable and can be replaced on-site while the storage shelf is operational.